Combined antenatal therapy with retinoic acid and tracheal occlusion in a rat model of congenital diaphragmatic hernia

Abnormal Fetal Lung of Hoxa1-/- Piglets Is Rescued by Maternal Feeding with All-Trans Retinoic Acid

Neonatal Hoxa1-/- piglets were characterized by dyspnea owing to the Hoxa1 mutation, and maternal administration with ATRA alleviated the dyspnea of neonatal Hoxa1-/- piglets. The purpose of this experiment was to explore how maternal ATRA administration rescued the abnormal fetal lungs of Hoxa1-/- piglets. Samples of the lungs were collected from neonatal Hoxa1-/- and non-Hoxa1-/- piglets delivered by sows in the control group, and from neonatal Hoxa1-/- piglets born by sows administered with ATRA at 4 mg/kg body weight on dpc 12, 13, or 14, respectively. These were used for the analysis of ELISA, histological morphology, immunofluorescence staining, immunohistochemistry staining, and quantitative real-time PCR. The results indicate that the Hoxa1 mutation had adverse impacts on the development of the alveoli and pulmonary microvessels of Hoxa1-/- piglets. Maternal administration with ATRA at 4 mg/kg body weight on dpc 14 rescued the abnormal lung development of Hoxa1-/- piglets by increasing the IFN-γ concentration (p < 0.05), airspace area (p < 0.01) and pulmonary microvessel density (p < 0.01); increasing the expression of VEGFD (p < 0.01), PDGFD (p < 0.01), KDR (p < 0.01), ID1 (p < 0.01), and NEDD4 (p < 0.01); and decreasing the septal wall thickness (p < 0.01) and the expression of SFTPC (p < 0.01) and FOXO3 (p < 0.01). Maternal administration with ATRA plays a vital role in rescuing the abnormal development of lung of Hoxa1-/- fetal piglets.

Prenatal Molecular Hydrogen Administration Ameliorates Several Findings in Nitrofen-Induced Congenital Diaphragmatic Hernia

Oxidative stress plays a pathological role in pulmonary hypoplasia and pulmonary hypertension in congenital diaphragmatic hernia (CDH). This study investigated the effect of molecular hydrogen (H₂), an antioxidant, on CDH pathology induced by nitrofen. Sprague-Dawley rats were divided into three groups: control, CDH, and CDH + hydrogen-rich water (HW). Pregnant dams of CDH + HW pups were orally administered HW from embryonic day 10 until parturition. Gasometric evaluation and histological, immunohistochemical, and real-time polymerase chain reaction analyses were performed. Gasometric results (pH, pO_2, and pCO₂ levels) were better in the CDH + HW group than in the CDH group. The CDH + HW group showed amelioration of alveolarization and pulmonary artery remodeling compared with the CDH group. Oxidative stress (8-hydroxy-2′-deoxyguanosine-positive-cell score) in the pulmonary arteries and mRNA levels of protein-containing pulmonary surfactant that protects against pulmonary collapse (surfactant protein A) were significantly attenuated in the CDH + HW group compared with the CDH group. Overall, prenatal H₂ administration improved respiratory function by attenuating lung morphology and pulmonary artery thickening in CDH rat models. Thus, H₂ administration in pregnant women with diagnosed fetal CDH might be a novel antenatal intervention strategy to reduce newborn mortality due to CDH.

Overexpression of miR-455-5p affects retinol (vitamin A) absorption by downregulating STRA6 in a nitrofen-induced CDH with lung hypoplasia rat model

Lung hypoplasia is the main cause of congenital diaphragmatic hernia (CDH)-associated death but pathogenesis remains unclear. MiR-455-5p is involved in lung hypoplasia. We hypothesized that nitrofen causes abnormal miR-455-5p expression during lung development and designed this study to determine the relationship between miR-455-5p, stimulated by retinoic acid 6 (STRA6), and retinol in a nitrofen-induced CDH with lung hypoplasia rat model. Nitrofen or olive oil was administered to Sprague-Dawley rats by gavage on day 9.5 of gestation, and the rats were divided into a nitrofen group and a control group (n = 6). The left lung of fetuses was dissected on day 15.5. The expression of miR-455-5p or STRA6 messenger RNA (mRNA) was determined by quantitative real-time polymerase chain reaction. Average integrated optical density (IOD) of STRA6 protein was determined by immunofluorescence histochemistry. The average retinol level was detected by enzyme-linked immunosorbent assay (n = 6 lungs, respectively). Compared with the control group, the nitrofen group exhibited significantly increased miR-455-5p expression levels (29.450 ± 9.253 vs 5.955 ± 2.330; P = .00045) and significantly decreased STRA6 mRNA levels (0.197 ± 0.097 vs 0.588 ± 0.184; P = .0047). In addition, the average IOD of the STRA6 protein was significantly lower in the nitrofen group (805.643 ± 291.182 vs 1616.391 ± 572.308, P = .015), and the average retinol level was significantly reduced (4.013 ± 0.195 vs 5.317 ± 0.337 µg/L, P = .000). In summary, the overexpression of miR-455-5p affected retinol absorption by downregulating STRA6 in the nitrofen-induced CDH with lung hypoplasia rat model, and this downregulation may be one cause of CDH with lung hypoplasia.

miR-455-5p Overexpression Reduces Rat Lung Alveolar Type II Cell Proliferation by Downregulating STRA6

miR‐455‐5p and retinoid signaling pathway and its membrane receptor, STRA6, are associated with lung development. Software copredictions indicate that the miRNA upstream of the STRA6 gene is miR‐455‐5p. We hypothesized that miR‐455‐5p participates in rat lung alveolar Type II cell proliferation by targeting STRA6 and designed this study to investigate the effects of miR‐455‐5p overexpression on rat lung alveolar Type II cells. Dual luciferase reporter gene assay was utilized to confirm the relationship between miR‐455‐5p and STRA6. An miR‐455‐5p‐expressing adenoviral vector was constructed and transfected into rat lung alveolar Type II cells. STRA6 protein expression was detected in rat lung alveolar Type II cells by Western blotting at 72 hr posttransfection. Retinol concentration was detected by ELISA at 72 hr posttransfection. The cell proliferation was detected by CCK8 assay at 24, 48, and 72 hr posttransfection. Our results showed that STRA6 is a target gene of miR‐455‐5p. STRA6 protein expression was significantly lower in the miR‐455‐5p‐overexpression group than in the NC group (0.615 ± 0.131 vs. 0.958 ± 0.246, P = 0.029). Similar results were observed for retinol concentration (2.985 ± 0.061 vs. 3.949 ± 0.118, P = 0.000). Rat lung alveolar Type II cell proliferation was lower in the miR‐455‐5p‐overexpression group than in the NC group at 24, 48, and 72 hr posttransfection (24 hr: 0.280 ± 0.184 vs. 1.354 ± 0.169 P = 0.026; 48 hr: 0.881 ± 0.016 vs. 1.992 ± 0.050 P = 0.001; 72 hr: 2.105 ± 0.148 vs. 2.937 ± 0.079 P = 0.016). In summary, miR‐455‐5p is associated with lung development. miR‐455‐5p overexpression downregulates STRA6, leading to reduced retinol concentration and rat lung alveolar Type II cell proliferation. Anat Rec, 302:2062–2069, 2019. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Pulmonary hypertension secondary to congenital diaphragmatic hernia: factors and pathways involved in pulmonary vascular remodeling

Congenital diaphragmatic hernia (CDH) is a severe birth defect that is characterized by pulmonary hypoplasia and pulmonary hypertension (PHTN). PHTN secondary to CDH is a result of vascular remodeling, a structural alteration in the pulmonary vessel wall that occurs in the fetus. Factors involved in vascular remodeling have been reported in several studies, but their interactions remain unclear. To help understand PHTN pathophysiology and design novel preventative and treatment strategies, we have conducted a systematic review of the literature and comprehensively analyzed all factors and pathways involved in the pathogenesis of pulmonary vascular remodeling secondary to CDH in the nitrofen model. Moreover, we have linked the dysregulated factors with pathways involved in human CDH. Of the 358 full-text articles screened, 75 studies reported factors that play a critical role in vascular remodeling secondary to CDH. Overall, the impairment of epithelial homeostasis present in pulmonary hypoplasia results in altered signaling to endothelial cells, leading to endothelial dysfunction. This causes an impairment of the crosstalk between endothelial cells and pulmonary artery smooth muscle cells, resulting in increased smooth muscle cell proliferation, resistance to apoptosis, and vasoconstriction, which clinically translate into PHTN.

Lessons from the Barn to the Operating Suite: A Comprehensive Review of Animal Models for Fetal Surgery

The International Fetal Medicine and Surgery Society was created in 1982 and proposed guidelines for fetal interventions that required demonstrations of the safety and feasibility of intended interventions in animal models prior to application in humans. Because of their short gestation and low cost, small animal models are useful in early investigation of fetal strategies. However, owing to the anatomic and physiologic differences between small animals and humans, repeated studies in large animal models are usually needed to facilitate translation to humans. Ovine (sheep) models have been used the most extensively to study the pathophysiology of congenital abnormalities and to develop techniques for fetal interventions. However, nonhuman primates have uterine and placental structures that most closely resemble those of humans. Thus, the nonhuman primate is the ideal model to develop surgical and anesthetic techniques that minimize obstetrical complications.